-T 



•X. 



3-1. 



^ndo 



^the 



inter. 



'^'nribiit 



es 



-°^3'geiiof 



^'" ^^ith th 



e 



V"' 



:e 



'-erofthe 

 combii 



les 



'^^ produces 

 ►vvth of ve- 



^f this Sec. 



getation ap. 

 all parts of 



, are known 

 It fimplyby 



tBelefs 



iiever 



; during the 

 (hops of the 



J vegetation 

 hich appears 



K 



ftorius 



have 



daily 



lofs 0^ 



el 



ither in r^' 



frona 



the at- 



30 



a 



^t^eikin^; 



itious 

 . but 



It 

 e 



> 



feeit^s 



Sect. X. 3. 3 



MANURES 



97 



to be f( 



of 



■ted firft for the purpofe of keeping the external furface of 

 ... _... from becoming dry, which would prevent the oxygen 

 the atmofphere from entering into the vegetable blood through them ; 

 fmce according to the experiments of Dr.Prieftley on animal men.- 

 branes the oxygen will only pafs through them, when they are ri^oift. 

 A fecond ufe of this great perfpiration is to keep the bark fupple by 

 its moifture, and thus to prevent its being cracked by the motion of 



a great part of this peripi- 



the branches in the wind 



rable matter is probably abforbed 



And though 



the Ikins of animal 



yet 



a 



on 



fo large a furface of leaves and 



o 



muchof 



ft 



flarily evaporate on dry and windy days. 

 One of the great difcoveries of modern chemiftry is the decom 



water, which is {hewn both by analyfis and fynthefis t 



3- 



pofiti 



confift of eighty-five hundredth parts of oxy 



of 



drog 



Ten, and fifteen of hy- 

 Hence a third great ufe of water in the vegetable economy 



probably owing to its ready decompofition by 



th 



organs of d 



ft 



fansuifi 



d fecretion. This is evinced firft 



the 



areat quantity of hydrogen, which exifts in the compofition of many 

 of their inflammable parts. And fecondly, from the curious circum- 

 flance, which was firft difcovered by the ingenious Dr. Prieftley, that 



the water, which they perfp 



hyperoxygenated 



d in confe 



quence always ready to part with its fuperabundance of oxygen, wh< 

 expofed to the fun's light ; from whence it may be concluded, th 

 part of the hydrogen, which was previoufly an ingredient of th 



lad been feparated from it, and u 

 further treated of in Section XlII 



fed in the vegetable economy 



I. 2. 



Add to this, that from the decompofition of water, when confined 

 in conta6l with air beneath the foil, the nitrous acid feems to be pro- 

 duced and ammonia, both which are believed ufeful to vegetation, as 

 mentioned in No. 2. 6. of this Se£lion. 



4. Befides the peculiar ufes of a great quantity of water, as above 

 cVcfcribed, the more common ufes of it both to vegetable and animal 



life. 



